Persist Telegram chats in DB, auto-save from webhooks, click-to-copy

- Add TelegramChat model (bot_id, chat_id, title, type, username)
- Chats auto-saved when bot receives webhook messages
- New API: GET/DELETE chats, POST discover (merges from getUpdates)
- Cascade delete chats when bot is deleted
- Frontend: click chat row to copy chat ID to clipboard
- Frontend: delete button per chat, "Discover chats" sync button
- Add 4 i18n keys (EN/RU) for chat management

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/lib/i18n/en.json

@@ -194,7 +194,11 @@
 		"rateSearch": "Search cooldown",
 		"rateFind": "Find cooldown",
 		"rateDefault": "Default cooldown",
-		"syncCommands": "Sync to Telegram"
+		"syncCommands": "Sync to Telegram",
+		"discoverChats": "Discover chats from Telegram",
+		"clickToCopy": "Click to copy chat ID",
+		"chatsDiscovered": "Chats discovered",
+		"chatDeleted": "Chat removed"
 	},
 	"trackingConfig": {
 		"title": "Tracking Configs",